A protein that appears to be unique to cystic fibrosis genotypes has been identified. Because of its interaction with mucociliary systems the protein has been termed the cystic fibrosis mucociliary inhibitor (CFMI). The purpose of this project is to purify and characterize the CFMI from culture media of fibroblasts and amniotic cells derived from cystic fibrosis genotypes. An antibody specific to the CFMI will be produced and will be utilized to develop quantitative assays that may lend to heterozygote detection and prenatal diagnosis of cystic fibrosis.